Considered inferior to Usopp Usopp Golden Pound. His +1 socket and marginally better stats/captain's ability do not outweigh the fact that his special takes 5 turns longer. In vast majority of battles, the minor extra damage Sogeking does is nowhere near close to balancing the fact that you have to stall 5 more turns for his special, and you cannot use it repeatedly as easily as for GPU.

Socket guide: don't socket him. He is one of the weaker Usopps. You should be using him as a socket for GPU. Once you max your first GPU, socket the second one. Then socket playable Usopps like Usopp A Pirate Who Lives by His Code or Impact Usopp, This one is not worth it, not until/unless Bandai gives us a better super evolution for him.